Global information networks are evolving rapidly toward Internet Protocol (IP)-based Next Generation Networks (NGNs) along with the dramatic development of computer and communication technologies. This means that wireless networks can provide various organizations or users with more abundant wireless services. Demands of these services for wireless resources are diversified greatly due to their different natures and contents. This diversity will be more apparent especially in a heterogeneous wireless-access network environment formed under coexist of various types of wireless technologies. At this time, there arises a high requirement on management of wireless communication resources.